Figure 1. Representative manganese-enhanced MRI (MEMRI) data of P7 wild type (WT; top row) and melanopsin knock out (KO; bottom row) mouse eyes following either dark (left column) or light (right column) adaptation. The white circle indicates the region of extraocular muscle used to normalize retinal signal intensities in this figure and in Figure 2. The same muscle-normalized signal intensity scale (far right) was used for all images and in all analyses. Retinal signal intensity data in Figure 2 were extracted from the central retina (0 to 30% of the panretinal extent or the region between the arrows). The width of each image is 4.14 mm.